How to pass cost value from cart js script?

Question

AJAX

Hello. There is a js code for the cart, where the total cost is deducted. I'm trying to pass it to post.php, where the payment form is already being processed. But the cost is not transferred, I'm trying to do it like this:

totalprice = (unitsprice + delcost).toFixed(2);
    $.ajax({
      url: "post.php",
      type: "POST",
      data: {"&amount" : JSON.stringify(totalprice)},      
    });

where totalprice is the total cost.
Then in the post.php file I try to get this value like this:

$data = "entityId=8ac9a4ca7a13eba8017a1dedeec37130" .
                json_decode($_POST["&amount"]) .
                "&currency=EUR" .
                "&paymentType=DB";

Initially, the php code looked like this:

$data = "entityId=8ac9a4ca7a13eba8017a1dedeec37130" .
               "&amount=92.00"
                "&currency=EUR" .
                "&paymentType=DB";

You need to replace the &amount value with mine from the totalprice variable in js

Answer 1

let totalprice = (unitsprice + delcost).toFixed(2);
$.ajax({
  url: "post.php",
  type: "POST",
  data: {
    amount: totalprice,
  },
});

$data = "entityId=8ac9a4ca7a13eba8017a1dedeec37130" .
        "&amount=" . $_POST["amount"] .
        "&currency=EUR" .
        "&paymentType=DB";